1. Field of the Invention
The present invention relates in general to automotive air conditioners, and more particularly to automotive air conditioners of a type employing a slide type air mixing door which, when sliding, varies a flow rate between heated air and cooled air which are mixed in an air mixing chamber before being led into a passenger compartment of the vehicle. More specifically, the present invention is concerned with a slide door unit or cassette detachably installed in the automotive air conditioner, which generally comprises a door housing, a slide door proper slidably held by the door housing and a driving mechanism for driving the slide door proper relative to the door housing.
2. Description of the Prior Art
In order to clarify the task of the present invention, an automotive air conditioner 100 using a known slide door arrangement will be briefly described with reference to FIG. 16, which is shown in Japanese Patent First Provisional Publication 11-254942.
The air conditioner 100 comprises a case 102 which defines therein an upstream air passage 104, a first downstream air passage 106, a second downstream air passage 108 and an air mix chamber 110. The first and second downstream air passages 106 and 108 have respective upstream mouth portions exposed to a downstream end of the upstream air passage 104 and have respective downstream portions merged with the air mix chamber 110. Air outlet openings 112 and 114 are formed at a downstream end of the air mix chamber, whose opening degrees are controlled by pivotal mode doors 116 and 118. An evaporator 120 is installed in the upstream air passage 104 and a heater unit 122 is in the first downstream air passage 106, as shown. Although now shown in the drawing, an air intake unit is arranged beside the case 102, by which outside/inside air is led into the upstream air passage 104, which then flows downward in such a manner as is indicated by thicker arrows.
A slide door mechanism SDM is provided in front of the mouth portions of the first and second downstream air passages 106 and 108 for varying the opening degree of the mouth portions of the passages 106 and 108.
The slide door mechanism SDM comprises generally a slide door proper 124, two pairs of guide pins 126a and 126b fixed to front and rear side ends of the slide door proper 124, and two pairs of arcuate guide grooves 128a and 128b formed in opposed side walls of the case 102 to slidably receive therein the guide pins 126a and 126b. The slide door proper 124 has at lateral lower sides respective racks (no numeral) which are meshed with respective pinion gears 130 which are coaxially connected through a shaft 132 whose both ends are rotatably held by the opposed side walls of the case 102. Although not shown, an electric actuator is arranged near the pinion gears 130 to drive the same. Thus, when the electric actuator is energized for a given time, the pinion gears 130 are rotated in one or other direction moving the slide door proper 124 to a desired position along a given way defined by the two pairs of guide grooves 128a and 128b. 
However, due to inherent construction, the above-mentioned conventional air conditioner 100 has several drawbacks which are as follows. First, movement of the slide door proper 124 along the given way tends to produce a rattling noise due to a rough sliding mating of the guide pins 126a and 126b with the guide grooves 128a and 128b. In fact, a certain clearance needed between each guide pin 126a or 126b and walls of the corresponding guide groove 128a or 128b for the movement of the guide pin relative to the groove causes a play of the slide door proper 124 during its movement, which induces the production of rattling noise. This undesired phenomenon become much severe when the guide pins 126a and 126b and the case 102 by which the guide grooves 128a and 128b are defined are constructed of same plastic materials. In this case, smoothed movement of the slide door proper 124 is not expected. Second, it needs a skilled and time-consuming assembling work for assembling the slide door proper 124 in a proper position of the case 102. That is, since the guide grooves 128a and 128b to which the guide pins 126a and 126b of the slide door proper 124 are to be engaged are formed in the inner walls of the case 102, the assembling work should be made awkwardly in such a limited space in the case 102.
It is therefore an object of the present invention to provide an automotive air conditioner which is free of the above-mentioned drawbacks.
It is another object of the present invention to provide a slide door unit which is suitable for the automotive air conditioner.
It is still another object of the present invention to provide a slide door unit which is characterized by smoothed movement of a slide door member relative to a door housing.
It is a further object of the present invention to provide a slide door unit in which, due to usage of a resilient structure defined by a pinion gear unit, a slide door member is constantly biased toward the door housing thereby to suppress undesired play of the slide door member.
It is a still further object of the present invention to provide a slide door unit which can be assembled with ease.
According to a first aspect of the present invention, there is provided a slide door unit for use in an automotive air conditioner, which comprises a door housing having a concave inner surface and laterally opposed side walls, the side walls having arcuate guide grooves respectively; a slide door member having a convex outer surface slidable on and along the concave inner surface of the door housing, the slide door member having a concave inner surface; racks provided on laterally opposed sides of the concave inner surface of the slide door member; guide pins secured to laterally opposed ends of the slide door member, the guide pins being slidably engaged with the arcuate guide grooves of the door housing; a pinion gear unit including two pinion gears and a shaft by which the pinion gears are connected, the pinion gear unit is rotatably held by the laterally opposed side walls of the door housing having the two pinion gears meshed with the racks respectively; and a resilient structure defined by each of the pinion gears of the pinion gear unit, the resilient structure biasing the pinion gears against the racks thereby pressing the guide pins against bottom walls of the corresponding arcuate guide grooves when the pinion gear unit is properly held by the door housing.
According to a second aspect of the present invention, there is provided a slide door unit for use in an automotive air conditioner, which comprises a barrel door housing having a concave inner surface and laterally opposed side walls each having a crescent shape; an arcuate guide groove formed at an inner surface of each side wall of the door housing; a guide pin entrance groove formed at the inner surface of each side wall of the door housing, the entrance groove extending from the arcuate guide groove to the outside of the side wall; a barrel slide door member having a convex outer surface slidable on and along the concave inner surface of the door housing, the slide door member having a concave inner surface; racks integrally formed on laterally opposed sides of the concave inner surface of the slide door member; two upper guide pins secured to upper portions of laterally opposed ends of the slide door member respectively, the two upper guide pins being slidably engaged with one zones of the arcuate guide grooves of the opposed side walls respectively; two lower guide pins secured to lower portions of the laterally opposed ends of the slide door member respectively, the two lower guide pins being slidably engaged with the other zones of the arcuate guide grooves of the opposed side walls respectively; a pinion gear unit including two pinion gears and a shaft by which the pinion gears are coaxially connected, the pinion gear unit being rotatably held by the side walls of the door housing having the two pinion gears meshed with the racks respectively; and a plurality of arcuate grooves concentrically formed in each of the pinion gears of the pinion gear unit to provide the pinion gear with a resiliency by which the pinion gears are biased against the racks thereby to press the guide pins against bottom walls of the corresponding arcuate guide grooves.
According to a third aspect of the present invention, there is provided a slide door unit for use in an automotive air conditioner, which comprises a barrel door housing having a concave inner surface and laterally opposed side walls each having a crescent shape; upper and lower arcuate guide grooves formed at an inner surface of each side wall of the door housing, the upper and lower arcuate guide grooves being arranged lengthwise; upper and lower guide pin entrance grooves formed at the inner surface of each side wall of the door housing, the entrance grooves extending from the respective upper and lower arcuate guide grooves to the outside of the side walls; a barrel slide door member having a convex outer surface slidable on and along the concave inner surface of the door housing, the slide door member having a concave inner surface; racks integrally formed on laterally opposed sides of the concave inner surface of the slide door member; two upper guide pins secured to upper portions of laterally opposed ends of the slide door member respectively, the two upper guide pins being slidably engaged with the upper guide grooves of the opposed side walls respectively; two lower guide pins secured to lower portions of the laterally opposed ends of the slide door member respectively, the two lower guide pins being slidably engaged with the lower guide grooves of the opposed side walls respectively; a pinion gear unit including two pinion gears and a shaft by which the pinion gears are coaxially connected, the pinion gear unit being rotatably held by the side walls of the door housing having the two pinion gears meshed with the racks respectively; and a plurality of arcuate grooves concentrically formed in each of the pinion gears of the pinion gear unit to provide the pinion gear with a resiliency by which the pinion gears are biased against the racks thereby to press the guide pins against bottom walls of the corresponding arcuate guide grooves.